The present invention relates to flexible circuits and more particularly to flexible circuits utilized in the automotive industry which can additionally incorporate relays for circuits.
In the most recent quarter century the utilization of electronics in automotive vehicles has increased significantly. For example, virtually all automotive vehicles have an engine control module to optimize the performance of the engine with regard to fuel efficiency and environmental emissions. Inflatable restraints have been added to enhance occupant safety in a crash situation. Advanced braking systems, such as anti-skid braking and traction control further enhance safe operation of the vehicle. Other electrical systems have been added or enhanced to increase the comfort of the vehicle.
The above mentioned additions and enhancements have resulted in a more complex wiring system which supplies power and signal transfer to and from various electrical components and controllers. Currently, much of the power and signaling requirements of a vehicle are supplied by hard conductive wiring, which is housed in a wiring harness. Fabrication of a wiring harness is a very labor-intensive operation. Installation and/or repair of a wiring harness can also be very time consuming and expensive.
Another disadvantage associated with the hard copper conductive wiring is the cost associated with the copper. For certain applications, the copper wire needed for signal transfer at a low electrical load can be a copper wire of a very small cross-sectional area. However, a minimum diameter of copper wiring is not determined by its electrical requirements. The minimum diameter of the wiring is determined by its frailty during the assembly process of the wiring harness and of the wiring of the vehicle.
To reduce the cost of automotive wiring harnesses a new type of electrical conduit has been provided. This new conduit is typically referred to as a flexible circuit. In a flexible circuit, a polymeric (or insulated metallic ribbon) substrate which is flexible, provides support for the various electrical conductor lines. The electrical conductors are then supplied by a foil that is affixed to the flexible substrate. Another flexible layer of polymeric material can cover the conductors on the flexible substrate.
Utilizing flexible circuits as a replacement for the prior wiring harnesses has been limited due to the particular problems faced by flexible circuits at the various component interfaces. For instance, the interface of the flexible circuit with a fuse box has been a particular limiting factor. To overcome those limitations, an inventive contact method has been provided in U.S. patent application Ser. No. 09/298,240 filed Apr. 22, 1999. Other examples of connector interfaces for flexible circuits can be found in U.S. Pat. Nos. 5,885,091 and 5,969,418.
Another problem with utilizing flexible circuits is in the use of relays. Relays typically are switches that have two contacts which are spring biased toward or away from each other, and are activated (closed or opened) by an electromagnetic force by a selectively excitable electromagnetic coil. Relays are typically provided for high current applications that require momentary application.
A preferred embodiment arrangement of a relay that utilizes a flex circuit is provided. The relay arrangement has a first substrate that may be a flex circuit or a conventional rigid circuit board. A first conductive membrane is connected on the first substrate. A second substrate which is flexible is provided. The second flexible substrate has a contact portion. In a first position, the second substrate contact portion is spaced away from the first substrate. In a second position, the second substrate contact portion is spaced adjacent to the first substrate.
A second conductive membrane is connected on the second substrate. A ferritic member is also connected on the second substrate. The ferritic member is adjacent to the contact portion.
A coil is provided. The coil has wire windings wrapped around a core for providing a magnetic field. The magnetic field causes the second substrate contact portion to move between the first and second positions against a flexural force of the second substrate.
It is an advantage of the present invention to provide an arrangement of a flex circuit relay.
Other features and advantages of various embodiments of the present invention will become more apparent to those skilled in the art from a reading of the following detailed description and upon reference to the drawings.